JP2532434B2 - Arc welding equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding apparatus for automatic welding used with a welding robot and a welding jig.

2. Description of the Related Art Conventional arc welding machines for automatic welding have a narrow welding speed range of 30 to 80 CPM and a low-speed arc welding machine for anti-automatic welding. The existing adjustments and operations such as wire feed amount / welding output adjustment, torch switch ON / OFF operation, and torch operation can be performed through the welding robot or welding jig.

Adjustment of the welding output is performed so that the arc will not be unstable and welding defects will not occur with respect to differences in the wire feed rate, the distance between the torch base materials, the welding position, and the shape of the weld joint. This is performed to set the state of the arc within a proper range.

Therefore, even when performing high-speed welding of 100 CPM or more by automatic welding, the welding output adjustment in the range of semi-automatic welding at a relatively low speed of 30 to 80 CPM is covered.

Problems to be Solved by the Invention As described above, in the conventional example, since the welding output control method in low-speed welding is directly applied to high-speed welding, welding defects such as undercut and humping characteristic of high-speed welding are eliminated. There are problems that easily occur. This problem is inconsistent with the main purpose of automatic welding in which the main purpose is to increase the welding speed.

The present invention solves the above-mentioned problems by configuring the welding output to be automatically controlled to an appropriate value according to the welding speed so that an appropriate welding output can be obtained even in high-speed welding, which has been a problem in the past. That is the purpose.

Means for Solving Problems In order to solve the above problems, the arc welding apparatus of the present invention performs welding based on three command signals which are a welding voltage command signal, a welding current command signal and a welding speed command signal input. It is provided with an output control circuit capable of selecting an optimum value from the welding output control waveform data stored in the condition data bank and performing welding output control.

Action With the above configuration, the optimum data for determining the output according to the welding speed is selected, so that the optimum welding output control waveform according to the welding speed can be obtained.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a rectifier that rectifies a three-phase AC power supply voltage. The output terminal of the rectifier 1 is connected to the primary winding of the main transformer 3 via the welding output control element 2, and the welding output control element 2 performs a switching operation to generate a high frequency voltage in the primary winding of the main transformer 3. appear. The high-frequency voltage generated in the secondary winding of the main transformer 3 is rectified by the rectifier 4, smoothed by the smoother 5, and supplied between the wire 15 and the base material 16 via the output terminal 6.

Reference numeral 22 denotes a robot main body, and a torch 14 is provided at a tip of the arm. Reference numeral 17 denotes a welding robot control device, which includes a torch switch command device 18, a welding speed command device 19, a welding current command device 20, and a welding voltage command device 21. The welding speed command signal output from the welding speed command device 19, the welding current command signal output from the welding current command device 20, and the welding voltage command signal output from the welding voltage / command device 21 are transmitted via the command value receiving circuit 24. Read into CPU23. The torch switch command signal output from the torch switch command device 18 is read by the CPU 23 via the torch signal receiving circuit 25. 10 is a data bank for welding current, voltage,
And data for obtaining the optimum output control waveform according to the speed are stored. The CPU 23 receives the welding current, voltage, and welding speed from the robot controller 17 and receives a command value receiving circuit 24.
, The data determined by the welding current value, the voltage value, and the welding speed is selected from the data bank 10, and this data is input to the output control circuit 9,
A welding output control waveform is formed based on this data.

Reference numeral 11 is a short-circuit arc discriminating circuit that discriminates between the short-circuit state and the arc state by detecting the voltage between the output terminals 6. The output of the short-circuit arc discrimination circuit 11 is input to the welding output control circuit 9. The output control circuit 9 receives the signal from the short-circuit arc discriminating circuit 11 and forms optimum output control waveforms for the short circuit and the arc based on the data from the CPU 23. The wire feed motor 13 operates by driving the wire feed command circuit 12 by the output of the welding output control circuit 9, and feeds the wire 15.

The pulse width modulation circuit 8 and the driver circuit 7 are sequentially driven by the output of the welding output control circuit 9 to switch the welding output control element 2.

In the above configuration, the operation content is as follows.
The welding speed command signal from the welding speed command device 19 of the welding robot control device 17, the welding current command signal from the welding current command device 20, and the welding voltage command signal from the welding voltage command device 21 are transmitted via the command value receiving circuit 24. Read by CPU23. CPU23
Selects the data determined from the above three command values from the data bank 10, and this data is input to the output control circuit 9. A signal indicating whether the welding output state is short-circuit or arc is input from the short-circuit arc valve circuit 11 to form an output control waveform based on the above data. The output of the output control circuit is input to the switching element 2 through the pulse width modulation circuit 8 and the driver 7 to control the welding output voltage. Another output control signal of the welding output control circuit 9 is
It is output to the wire feeding command circuit 12 to control the wire feeding speed.

Here, the command value receiving circuit for welding current, voltage and speed will be described. Normally, the output signal from the robot controller 17 is an analog signal, so if the input stage of the welding output control circuit 9 has a digital input configuration, the A / D conversion and the input of the welding output control circuit 9 have an analog input configuration. In some cases, it functions to perform matching between the input stage of the welding output control circuit 9 and the output stage of the robot controller 17, such as analog amount adjustment. If the output signal from the robot controller 17 is a digital signal, the command value receiving circuit 24 may be omitted. The torch switch signal receiving circuit operates so as to convert the torch switch signal from the robot into a signal whose timing can be read by the CPU.

As for the welding output control characteristics, the data is selected so that the optimum analog control waveform can be obtained depending on the welding current, voltage, and speed. According to our detailed experimental results, when the welding speed is low, the short-circuit opening Select data that gives a control waveform that will increase the subsequent welding output, and increase the welding output reduction rate after opening the short circuit. It was found that when the welding speed was high, good welding results could be obtained by selecting data that provided a control waveform that would lower the welding output after opening the short circuit. Also, when the welding speed is low, select the data that can obtain the control waveform that increases the welding output reduction rate after opening the short circuit,
It has been found that when the welding speed is high, good welding results can be obtained by selecting the data that can obtain the control waveform that reduces the reduction rate of the welding output after opening the short circuit.

FIG. 2 shows how the limit speed at which welding can be performed using the welding power source having the control characteristics of the present invention changes depending on the welding output reduction rate after the short circuit is opened.

Generally, when the welding speed becomes high, a welding defect characteristic of high-speed welding such as undercut or humping is likely to occur, but when the welding output reduction rate is changed by the configuration of the present invention, the welding limit speed is greatly improved. .

That is, it is possible to significantly improve the welding performance by obtaining the welding output control waveform that can obtain the welding output reduction rate after opening the short circuit suitable for the welding current, voltage and welding speed, which is effective for improving the welding performance. It turned out to be the target.

FIG. 3 shows the relationship between the welding output reduction rate and the amount of spatter generated after the short circuit is opened in low speed welding (50 CPM). Note that this is the case of CO ₂ welding, where the wire diameter used is 1.2 mmφ and lap fillet welding. The spatter generation amount is a large factor that determines the quality of welding in terms of appearance and maintenance around the torch, but the larger the welding output reduction rate, the smaller the spatter generation amount and the better welding results can be obtained.

Next, a configuration example of the data bank will be described. In FIG. 4, reference numeral 10 shows the arrangement of the data V in the data bank. An array corresponding to the welding current command value is selected among the welding currents I ₁ , I ₂ , ..., I _n based on the welding current joining signal input to the CPU 23. Further, the welding speed command signal input to the CPU 23 selects an array corresponding to the welding speed command value among v ₁ , v ₂ , ..., V _n . FIG. 4 specifically shows only the data array when the welding current command value is I ₁ . When the welding current command value is I ₁ , the welding speed command value v ₁ , v
_2, ..., the data sequence V _1, V ₂ corresponding to v _n, ..., V _n is selected. Also, by the welding voltage command signal input to the CPU23,
Data corresponding to the welding voltage command value is selected. When the welding current command value is I ₁ and the welding speed command value is v ₁ , the data is selected from the data array V ₁ . Data V ₁₁ , V ₁₂ , V ₁₃ , ..., V ₁₉ are stored in the data array V ₁ , and data (for example, V ₁₂ ) selected by the welding voltage command value is determined and output.

Other welding current command other than I ₁ values _{I 2, I 3, ...,} I 1 in the case of I _m
It has a table similar to. As described above, the welding output control waveform is determined by these data.

As described above, the example shown in FIG. 4 shows a configuration in which individual control conditions are written in the data bank and read out according to the input conditions. However, a configuration in which the control conditions are calculated according to the input conditions can be easily realized. it can.

Effects of the Invention As described above, according to the present invention, the following unique effects are exhibited.

(1) Appropriate welding output waveform control can be performed according to the welding speed, current, and voltage, and welding performance such as reduction of spatter and increase of the welding speed limit can be improved.

(2) The user does not need to adjust the welding output waveform parameter and the welding condition setting is easy.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an arc welding machine showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing a relationship between a welding output reduction rate and a welding speed limit, and FIG. 3 is a welding output reduction rate and spatter generation. FIG. 4 is a block diagram of the data bank shown in FIG. 9: welding output control circuit, 19: welding speed finger command device,
20 …… Welding current command device, 21 …… Welding voltage command device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Matsumoto Shomitsu 1006 Kadoma, Kadoma City, Matsushita Electric Industrial Co., Ltd. (72) Inventor Naoki Kawai 1006 Kadoma, Kadoma City, Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideyuki Oyama 1006 Kadoma, Kadoma-shi, Matsushita Electric Industrial Co., Ltd. (56) References JP-A-59-21473 (JP, A)

Claims (1)

(57) [Claims] 1. A consumable electrode type arc welding apparatus, the output of which is controlled by three command signals of a welding current command signal, a welding voltage command signal, and a welding speed command signal, based on the above three command signals, a welding condition data bank. Arc welding equipment equipped with an output control circuit that controls the welding output by selecting the optimum value from the welding output control waveform data such as the welding output reduction rate after the short circuit is released and the welding output stored in.